This application is based on Patent Application No. 165615/1998 filed on Jun. 12, 1998 in Japan, the content of which is incorporated hereinto by reference.
1. Field of the Invention
The present invention relates to a printing system and a printing method in which a printing apparatus prints an image according to print data transmitted from a control apparatus.
2. Description of the Prior Art
Generally, a print head used in an inkjet printing apparatus ejects ink through ink paths that form a plurality of nozzles or ink ejection orifices. In the printing apparatus using such a print head, there may be minute variations in shape among the nozzles forming ink paths and also errors in the nozzle shapes during the nozzle forming process. Because of these variations, it is often not possible to produce a uniform image by ejecting inks onto a print medium even when a command signal to form a uniform image is issued.
A method for correcting unevenness in print density, the cause of uneven image, and for making the density uniform is already known as head shading (HS).
FIG. 1 is a schematic block diagram of an apparatus that actually employs the head shading (hereinafter also referred to as xe2x80x9cHSxe2x80x9d) technique. The apparatus shown in FIG. 1 incorporates three systems, a reading unit (image exposing unit) 101, an image processing section 102, and a print (image forming) section 103. A conventional HS technology will be described below.
In FIG. 1, the reading unit 101 reads an original document and inputs a result of printing to obtain a density pattern required to perform HS. The image processing section 102 performs calculation processing on an image read by the reading unit 101, such as color correction and value determination processing (n=2, 3, 4 . . . ). The HS processing is also included in these calculation processing. The image forming section 103 takes in data, which was read by the reading unit 101 and processed by the image processing section 102, and then, based on this data, forms an image on a print medium by each print head 104.
In the printing apparatus of this configuration, the image forming section 103 forms an image on a print medium by using the print heads 104 according to a test pattern that is used to form an image of a specified density. The result of printing is read by the reading unit 101. The data read by the reading unit 101 is sent to the image processing section 102 where it is used to generate data required to perform HS processing (hereinafter referred to as xe2x80x9cHS dataxe2x80x9d). The HS data 105 is used to correct density-varying spots observed in the printing result produced by each of the print heads 104. That is, the print heads 104 each have a plurality of ink paths that form nozzles or ink ejection orifices and, when there are variations in the amount of ink ejected from these ink paths, density-varying spots are formed in the printing result. The HS data 105 is used to correct the density-varying spots and make them inconspicuous. That is, the HS data 105 is used as data for directly correcting an image input signal from the reading unit 101 for each print head 104. Based on the corrected output signal value, the print heads 104 in the image forming section 103 print an image.
There is a print system which has configured independently of each other the original exposing section (reading unit), the image processing system and the image forming section, like a system consisting of an image scanner, a computer terminal equipment and a printer. As to this system a variety of improvement proposals have been made, which include Japanese Patent Application Laid-Open Nos. 8-156932, 8-156803, 8-156813, 8-156820, 8-156822 and 8-156802.
One of these proposals deals with a case where a plurality of printing apparatuses are connected to a computer terminal equipment. In this configuration, correction information on all printing apparatuses which may be connected to the computer terminal equipment is constructed into database and stored in advance in a storage device connected to the computer terminal equipment. When printing, the computer terminal equipment sends a serial number to a printing apparatus to check the detail of the printing apparatus. Based on the result of the check, the computer uses the correction information corresponding to that printing apparatus and performs printing. In this way, the printing apparatus to be operated and the corresponding correction information are matched. Of the above proposals some include date information in the management of the correction information.
In the above proposals, however, the correction information unique to a particular printing apparatus exists separately and independently of the printing apparatus. Thus, the user must obtain in advance correction information about all the printing apparatuses that may be connected to the computer terminal equipment and manage these information. Further, as the number of printing apparatuses increases, the correction information on these printing apparatuses is accumulated in the storage device connected to the computer terminal equipment, thus increasing the amount of data stored. An increase in the accumulated data in turn makes erroneous operations and other troubles on the part of the user more likely.
An object of the present invention is to provide a printing system and a printing method, both capable of simplifying the management of information on individual printing apparatuses.
In a first aspect of the present invention, there is provided a printing system comprising:
a printing apparatus capable of printing an image according to print data on a print medium by using a print head having a plurality of print elements; and
a controller for sending the print data to the printing apparatus;
wherein the printing apparatus has first and second holding means for holding first unique information unique to the printing apparatus and second unique information unique to the print head, respectively;
wherein the controller includes:
first and second registration means capable of registering the first and second unique information sent from the printing apparatus, respectively;
a request means for requesting the printing apparatus to send the second unique information when the registered content of the first and second registration means does not agree with the first and second unique information in the printing apparatus; and
a conversion means for converting the print data according to the second unique information registered in the second registration means.
In the second aspect of the present invention, there is provided a printing method comprising the steps of:
sending print data from a controller to a printing apparatus; and
printing an image on a print medium according to the print data by using a print head having a plurality of printing elements;
wherein the printing apparatus sends unique information unique to the print head to the controller, and the controller converts the print data according to the unique information and sends the converted print data to the printing apparatus.
The present invention has stored in individual printing apparatuses correction information unique to each printing apparatus. A controller such as a computer terminal equipment requests unique information as required from a desired printing apparatus connected to it. This can eliminate the work on the part of a user, including preparation and management of unique information corresponding to the individual printing apparatuses.
Further, because individual printing apparatuses hold their unique information respectively, the controller such as a computer terminal equipment does not need to pool the unique information on individual printing apparatuses. The storage device on the controller side needs only to hold unique information on the printing apparatuses currently connected to the controller. For example, when one printing apparatus is selectively connected to the controller, only the unique information on that printing apparatus needs to be registered in the controller, thus it is prevented that the amount of data stored in the storage device on the controller side from increasing.
The unique information on individual printing apparatuses to be registered in the storage device on the controller side can be changed and updated for each print head. For example, by managing date data, version of information, and serial numbers, it is possible to automatically match the printing apparatuses to their corresponding unique information without the user having to become conscious of their correspondence.
As a result, the burden of the user is alleviated, allowing the user to easily establish the correspondence between the printing apparatuses and their unique information and to obtain appropriate printed result easily and reliably.
Further, in the invention the unique information corresponding to a print head installed in a printing apparatus is held in the printing apparatus and, at time of printing, the unique information is downloaded from the printing apparatus to the controller. The controller uses the downloaded unique information in the conversion processing such as correction of print data. This enables an overall management of the print heads in the printing apparatuses and their corresponding unique information.
Therefore, it is not necessary to manage the unique information on printing apparatuses separately by the printing apparatuses and the controller, as has been done in the conventional printing system. Further, in a storage device connected to the controller such as a computer terminal equipment, there is no need to manage a plurality of unique information, such as HS data of the printing apparatuses to be connected to the controller, as has been required conventionally.